---
description: >-
  In-depth notes regarding different forest trust configurations and abuse
  techniques.
---

# Forest Trust Abuse

A trust is a kind of relationship established between two or more Active Directory domains to facilitate resource management and authentication.

The following are the possible types of trust configurations:

* `Parent-child`: Two or more domains within the same forest. The child domain has a two-way transitive trust with the parent domain, meaning that users in the child domain `child.domain.com` could authenticate into the parent domain `domain.com`, and vice-versa.
* `Cross-link`: A trust between child domains to speed up authentication.
* `External`: A non-transitive trust between two separate domains in separate forests which are not already joined by a forest trust. This type of trust utilizes [SID Filtering](forest-trust-abuse/sid-filter-bypass) or filters out authentication requests (by SID) not from the trusted domain.
* `Tree-root`: A two-way transitive trust between a forest root domain and a new tree root domain. They are created by design when you set up a new tree root domain within a forest.
* `Forest`: A transitive trust between two forest root domains.
* [ESAE](https://docs.microsoft.com/en-us/security/compass/esae-retirement) or [PAM Trust](forest-trust-abuse/cross-forest-attacks/abusing-pam-trusts): A bastion forest used to manage Active Directory.

Trust can either be transitive or non-transitive: in a transitive trust, the relationship is extended to the child domain trusts, in a non-transitive trust the child domain itself is the only one trusted.

Trusts can be set up in two directions:

* One-way: a user in the trusted domain can access resources in a trusting domain
* Bi-directional: users from both the trusting and trusted domain can access resources from the other domain.

{% hint style="warning" %}
Remember that the direction of access is always opposite to the direction of the trust.
{% endhint %}
